Source : Webster's Revised Unabridged Dictionary (1913)

Sphenoid \Sphe"noid\, a. [Gr. ???; sfh`n a wedge + e'i^dos form:
   cf. F. sph['e]no["i]de.]
   1. Wedge-shaped; as, a sphenoid crystal.

   2. (Anat.) Of or pertaining to the sphenoid bone.

   {Sphenoid bone} (Anat.), an irregularly shaped bone in front
      of the occipital in the base of the skull of the higher
      vertebrates. It is composed of several fetal bones which
      become united the adult. See {Alisphenoid},
      {Basisphenoid}, {Orbitosphenoid}, {Presphenoid}.

Source : WordNet®

sphenoid bone
     n : butterfly-shaped bone at the base of the skull [syn: {sphenoid},
          {os sphenoidale}]